Mechanical decoder



March 28, 1967 R. J. BELANGER 3,311,880

MECHANICAL DEGODER Filed April 11, 1963 -5 Sheets-Sheet 2 '50 CODE SET CODE 5! CHANGE 5on CHANGE lNPuT 3 SNPUT ANNEL\ HANNELZ NORMAL RMAL ' oooooooooo INVENTOR. ROBE/27 J. BELANGE AGENT March 28, 1967 R. J. BELANGER 3,311,880

MECHANICAL DECODER Filed April ll, 1963 5 Sheets-Sheet 4 DRWE INVENTOR POBE/W'JBELANGBQ AGENT March 28, 1967 R. J. BYELANGIER 3,311,880

MECHANICAL DECODER Filed April 11, 1963 5 Sheets-Sheet 5 5 CODE CHANGE CYCLE LUWT O SWXTCHES sw H TEJCOMM. \NPUT W If .9 CHANNEL I: 58

CODE T N.C. CH COMM SOLENOID H 57 3M I x To COMM ToCOM \NDUT W. i CHANNEL 2 I 9 N. i ;g SOLENO\D [2 RESET awn-cw RESET, QHANN EL F1 RsT $ECOND svv \TCH swrrcH PosrnoN Posmo N ZERO L NORMAL CHANNEL 1 2 4 5 CHANNEL 50 I 3 l ROBHQTJBLLA N651? INVENTOR.

United States Patent Ohio Filed Apr. 11, 1963, Ser. No. 272,397 20 Claims. (Cl. 340-147) This invention relates to a storage device of the type generally known as a decoder and more particularly to an electromechanical decoder.

There is a great need both in the military and civilian market for a reliable device that is capable of being operated upon receipt of a proper message only, to thereby prevent unauthorized use or tampering of equipment that is ultimately being controlled and operated by the decoder. Devices of the type to be described are usually secreted in the device being controlled with access to the decoder limited to input channels over which the proper coded message is sent. In the commercial field such devices as gates, bank doors, communication systems, would require that the device by physically located within the element being safeguarded and made inaccesible to the operator except by means of the channels over which the coded signals are transmitted. In the military field such devices have great utility in preventing unauthorized operation of explosives or missiles without first transmitting the proper coded signals over the input channels. For missile protection it is envisioned that the decoder will be physically located on the missile itself, thereby physically insu'ring that access is limited to the input channels only.

In this invention, there is disclosed a plurality of individually controlled switches located in an ordered rela tionship. These switches are preferably located on a drum and are sequentially interrogated to determine the paths that are selected by the preset switches. For any given switch there is only one single preferred path. The first of the switches in the ordered relationship is interrogated by sending a pulse from the input channel into the first switch in order to select the preferred preset path. Upon selecting the preferred path of the first switch, the interrogating signal is automatically channeled to a switch selecting means in the form of a solenoid stepping generator which advances the drum mechanism containing the switches to the next switch position in the ordered relationship. The interrogating procedure is then repeated for the second switch and upon selecting the preferred path for the second switch the switch selecting means is energized again as previously described. This process continues for the total number of switches present. Upon the succesful interrogation of the preferred path in the last switch position of the switches in the defined ordered relationship, an output circuit is established to the utilization device that is being protected.

In the preferred embodiment, the decoder sequentially examines a digital code having a plurality of bit positions for coincidence with .a mechanically stored code. The number of bit positions is determined by the number of switch positions. For example, in one embodiment 18 switch positions were provided on a rotary drum thereby requiring an 18 bit positions digital code for proper interrogation. The drum mechanism containing the switches is geared to an output commutator which is rotated sequentially from its starting position after each successive verification of a proper bit of information. Receipt of each proper bit causes the drum to advance to the next succeeding storage position thereby advancing the output commutator. Receipt of the last proper digital bit completes the rotation of the commutator to provide the final output signal transmitted to the utilization device. Upon receipt of a false bit which is defined 331L386 Patented Mar. 28, 1967 as a bit which selects an improper path causes a reset circuit to be energized which trips a mechanism causing the drum to return to the original starting position. In addition, actuation of the reset mechanism opens the input channel circuits transmitting the input code thereby preventing the receipt of additional code information by the decoder. The decoder wil remain inoperative until a reset signal is received by the decoder over a separate circuit. The reset signal is designed to energize a reset circuit for closing the input channel circuits thereby enabling the decoder to receive additional messages. An auxiliary circuit controlled by the reset circuit makes the code less vulnerable to detection by counting the number of successive resets or errors. The number of resets is limited and preset to a number less than the number of switch positions which, if exceeded, will open all circuits to the decoder thereby effectively preventing any further operation of the decoder until the circuits are manually reset by authorized personnel having physical access to the decoder. The decoder also contains circuitry for remotely setting and changing the code without requiring physical access thereby insuring that installation workers, overhaul personnel or anyone else viewing the decoder will not gain advance knowledge of the code.

Further objects and advantages of this invention will be made more apparent by referring now to the accompanying drawings wherein:

FIG. 1 is a plan view of a preferred embodiment of a mechanical decoder;

FIG. 2 is a cross section view of the decoder taken along line 2-2 of FIG. 1;

FIG. 3 is a simplified pictorial view of the rotatable drum;

FIG. 4 is a cross section of FIG. 3 taken along lines 4-4 illustrating the drum operating means;

FIG, 5 is a cross section of FIG. 2 taken along lines 5-5 illustrating one of the plurality of switches;

FIG. 6 is a schematic diagram illustrating the mechanical and electrical functions of the decoder;

FIG. 7 is a cross section of FIG. 1 taken along lines 77 illustrating the mechanism for resetting the drum in response to an incorrect code or code change signal;

FIG. 8 is a cross section of FIG. 7 taken along lines 8-8 illustrating the reset mechanism gear train;

FIG. 9 is a combined schematic diagram and exploded view of the reset mechanism gear train illustrating the interconnections necessary for the code changing mode and electrical resetting mode;

FIG. 10 illustrates a feature for erasing the code whenever the decoder is mechani-cally moved from a preferred position;

FIG. 11 illustrates the coded input signals for controlling the decoder.

The mechanical decoder described and illustrated in this invention represents a preferred embodiment for serially examining an eighteen bit digital code for coincidence with a stored code and in response to the proper receipt of the input code signals to operate an output means. The decoder upon receipt of an improper bit which may be of the wrong plurality or time sequence will refuse to accept an additional input until a reset pulse is received from a separate input preferably located in a remote location. In the broad sense, the decoder verilies the received input code against the stored code and generates an outputindication that the received code has been verified.

Referring now to FIG. 1, FIG. 2 and FIG. 3, there is to thereby establish one of the paths as a preferred path. A path is selected and a signal transmitted over the selected path. If the selected path is the preferred path, then a circuit is established for advancing the decoder to the next switch position; however, if the path selected is not the preferred path than an error is indicated which prevents the decoder from receiving further input codes until the error is acknowledged by a rest circuit. The error is recorded in a preset counter regardless of whether it was caused by tapering, equipment malfunction or simple transmission error. Exceeding a preset number of errors will open all circuits to the decoder preventing further interrogation.

In the preferred embodiment, there is shown a code wheel drum 10 arranged to be rotated by either of two rotary solenoids 11 and 12 by means of ratchet wheels 13 and 14 located on opposite sides of the drum 10. Spring loaded pawls 15 and 16 bear against ratchet wheels 13 and 14 respectively and are individually controlled by the rotary operation of solenoids 11 and 12. FIG. 4 more fully illustrates the operation of pawl 16 on ratchet wheel 14. The drum 10 mechanically drives an output commutator 17 by means of gears 18 and 19. Each properly received coded input bit is arranged to rotate the drum 10 a given amount by energizing either solenoid 11 or 12. For an eighteen switch drum 10 an eighteen bit code must be properly received in order to rotate the output commutator switch 17 the necessary amount for operation. The particular type of output is usually dicated by the requirements of the system being controlled and may include a direct mechanical movement or the closing of discreet switches in a preferred sequence as illustrated to thereby operate and control a remote utilizing device not illustrated. The output commutator 17 illustrated will usually rotate less than one revolution of the drum 10 thereby requiring gear 18 to have a smaller diameter than gear 19.

The cooperation of the defined elements will be more understandable by referring now to FIGS. 3 and 5. The code wheel drum 10 consists of five individual segments 20, 21, 22, 23 and 24 electrically divided into eighteen switch positions which are each presettable by means of eighteen separate contactor actuating rods 25. There is one actuating rod 25 for each of the eighteen switch positions. The contactor actuating rod 25 is arranged to establish a first and second electrical path that will either electrically interconnect segments 20 and 21 and segments 22 and 24 or electrically interconnect segments 20 and 22 and 23 with 24. The mechanical code position is therefore determined by the position of the actuating rod 25 and the particular paths that are established when the rods are preset.

The detailed operation of the commutator actuating rods 25 is more fully illustrated in connection with FIG. which illustrates a cross section of the code wheel drum taken along line 55 of FIG. 2. A first position for the actuating rod 25 is shown in solid lines and a second position of the rod is shown in dotted lines 2511. The preferred path for either position is the path not including segment 22. Each contactor actuating rod 25 is preferably circular in cross section and located parallel with the axis of the code wheel drum 10 just below the surface of the electrically conductive segments 20, 21, 22, 23 and 24. As the cross section illustrates, segments 20 and 24 contain electrically conductive extensions 26 and 27 which are each extended around the openings that accepts the actuating rod 25 to a point just below the center segment 22. The defined electrical extensions 26 and 27 are insulated from each other and also insulated from segments 21, 22 and 23. The contactor actuating rod 25 contains a pair of shorting bars 28 and 29 that preferably completely encircle the rod 25 on the surface thereof. With the contactor actuating rod 25 in the first position as illustrated by the solid lines, the shorting bar 28 effectively shorts segment 22 with segment 20 through the electrically conductive extensions 26. Shorting bar 29 electrically connects segment 23 with segment 24 through electrically conductive extension 27. The effect is that placing the actuating rod 25 in the position illustrated by the solid lines will effectively short segments 20 with 22 and segments 23 with 24. Placing the actuating rod 25 in the position illustrated by the dotted lines 25a has the effect of moving shorting bars 28 and 29 to the position illustrated as 28a and 29a. The effect is to short segments 20 and 21 together by means of bar 28a and in a similar manner segments 22 and 24 are shorted together by means of bar 29a.

The interaction of the described elements will be best understood by referring to FIG. 3 where there is shown two input channels 30 and 31, one for each path. The successful operation of the decoder is acheived by selecting the channel having the preferred preset path as determined by the position of the contactor actuating rods 25. The code wheel drum 10 is mechanically arranged to always start at a predetermined first switch position. The first step in interrogating the decoder is to select which of the input channels 30 or 31 to use in sending the first interrogating pulse. Assuming that input channel 30 is selected, a substantially square pulse is generated and transmitted from input channel 30 through a normally closed code change switch 32 labelled normal to a brush contactor 33 electrically contacting segment 20. Assuming also that the contactor actuating rod 25 for the first switch position is in the dotted line position as illustrated in FIG. 5, an electrical circuit will be established from the segment 20 to the segment 21. The interrogating pulse will pass from the segment 21 through a brush contactor 34 to the normally open side of the code change switch 32 labelled code change, through a normally closed cycle limit switch and ultimately to the rotary solenoid 11 which is then energized. Energizing the rotary solenoid 11 rotates the spring loaded pawl 15 in a direction opposite to the drum rotation an amount sufficient to allow the pawl to escape to the next position on the ratchet wheel 13. The code wheel drum 10 is not rotated until power is removed from the solenoid 11. The solenoid actuating arm which controls the pawl 15 is additionally spring biased in the direction of rotation of the drum and it is the biasing spring (not illustrated) that actually provides the force for rotating the code wheel drum 10 when power to the solenoid is removed. Encgrizing the rotary solenoid 11 simply advances the pawl 15 the necessary number of teeth on the ratchet wheel 13 against the biasing spring force.

The code wheel drum 10 is now in position for receiving the next input pulse at the second switch position. For the second switch position, we will assume that the contactor actuating rod 25 is in the position illustrated in FIG. 5 by the solid lines 25. We will also assume that the next interrogating pulse is transmitted through the input channel 31. The interrogating pulse from the input channel 31 will pass through the normally closed contacts of a code change switch 35 labelled normal and then to a brush contactor 36. With the contactor actuating rod 25 positioned as indicated, an electrical current path will exist from segment 24 to segment 23. A brush contactor 37 contacting segment 23 will carry the interrogating pulse to the normally open portion of the code change switch 35 labelled coded code change, through a normally closed cycle limit switch and then to the rotary solenoid 12 which is then energized. As indicated previously in connection with the rotary solenoid 11, the energizing of rotary solenoid 12 will rotate the pawl 16 a distance that is sufficient to allow the pawl to escape to the next tooth position. When the interrogating pulse clears the system, the solenoid 12 is deenergized thereby allowing the biasing spring (not illustrated) to advance the code wheel drum 10 to the third switch position.

A review of the operation will show that receipt of a proper interrogating pulse on the proper input channel will operate either the rotary solenoid 11 or the rotary solenoid 12.

The following discussion will illustrate the effect of transmitting an incorrect interrogating signal. For this next illustration, we will assume that the contactor actuating rod 25 associaed with the third switch position is in the position illustrated in FIG. 5 by the rod 25 shown in solid lines. We will assume further that input channel 30 is selected for the interrogating signal. As described previously, the interrogating pulse will be generated on the input channel 30 and will pass through the normally closed contacts of the code change switch 32 to the brush contactor 33 to the segment 20. A review of FIG. 5 will show that segment 20 is electrically connected through extension 26 to segment 22 by means of the shorting bar 28. The interrogating signal will pass from the segment 22 through a brush contactor 38 contacting the segment 22 directly to a reset solenoid 39 which is then energized. A review of the circuits and available positions of the contactor actuating rod 25 will show that an improper interrogating pulse will always energize and operate the reset solenoid 39 which incidentally opens both cycle limit switches. FIG. 6 shows in schematic form the electrical equivalent for the mechanical interconnections illustrated in FIGS. 3 and 5.

Referring now to FIG. 7, there is shown the decoder reset mechanism that is energized whenever the reset solenoid 39 is energized due to an incorrect input signal. As mentioned previously, energizing the reset solenoid 39 causes the code wheel drum to return to the first switch starting position. FIG. 7 shows an end view of the code Wheel drum 10 containing the ratchet wheel 13. The movable pawl is controlled by the rotary solenoid 11 in FIG. 3 and is located on one side of the drum 10 while the movable pawl 16 controlled by rotary solenoid 12 in FIG. 13 is located on the other side of the drum. Not previously illustrated is a keeper 40 hearing against the ratchet wheel 13. There is an additional keeper on the other side (not illustrated) bearing against ratchet wheel 14. Only one keeper is actually needed, however, in order to balance forces, two are preferred. The keeper 40 is necessary in order to keep the code wheel drum 10 from being rotated backwards during the operation of pawls 15 or 16. The normal operating position of the keeper and pawls is shown in solid lines. The reset solenoid 39, when energized, generates a rotary motion in a clockwise direction. A face plate 39a is mounted concentrically with the shaft of the solenoid 39 but independent thereof and contains equally spaced release pins 41, 42, 43 and 44. A ratchet wheel 45 concentric with but independent of the shaft of the solenoid 39 is attached to the face plate 39a for moving the face plate. A movable arm 46 is mounted and attached to the shaft of the reset solenoid 39 and moves as the shaft moves. One end of the arm 46 contains a spring loaded pawl 47 which engages the ratchet wheel 45. Energizing the reset solenoid 39 rotates the arm 46 in a clockwise direction to the vertical dotted line position indicated by 46a. The pawl 47 is free to detent over the teeth on the ratchet wheel 45 in a nondriving relationship into a new driving position. The arm 46 will remain in position 46a as long as the solenoid 39 is energized. When the solenoid 39 is deenergized, the arm 46 is biased back to the original position as shown by the sol-id lines by a spring not illustrated. The process of returning the arm 46 to the solid line position causes the pawl 47 to rotate the ratchet wheel 45 and face plate 39a. The face plate 391: is rotated a distance sufficient to place the nearest pin 42 in close proximity to the vertical position of arm 46a.

A tripping lever 48 is externally mounted and arranged to contact the pawl 15 and the fixed keeper 40 at one end. An extension arm, similar to lever 48 (not illustrated) and moved as lever 48 moves, contacts the pawl 16 and 6. keeper on the other side of the drum 10. Whenever lever 48 is moved, the pawls 15 and 16 and keeper 40 are cammed into the dotted position which allows the drum 10 to return to the first switch position. The other end of the tripping lever 48 contains a cam wheel 49 arranged to be contacted and driven in a downward position by one end of the arm 46 whenever the reset solenoid 39 is energized and the arm is in the vertical position 46a.

A spring biased latch 50 is mounted and positioned to accept and hold the cam wheel end of the tripping lever 48 whenever the arm 46 pushes the cam wheel 49 in a downward direction. In addition, the latch 50 projects into the rotational arc traversed by the pins 42, 43, 44 and 41. Before decoder can again be interrogated, it is necessary to purposefully energize the reset solenoid along a separate line. Energizing the solenoid 39 will repeat the process just described with the exception that the closest pin 42 will now trip the latch 50 allowing the lever 48 to return to the normal solid line position.

The cooperation and action of the reset solenoid 39 and code changing apparatus will be made more apparent by referring to FIGS. 6, 8 and 9. FIG. 6 is a schematic diagram illustrating the interaction between the mechani cal portions and the electrical portions. FIG. 8 is a cross section of the reset solenoid 39 in FIG. 7 taken along lines 8-8. FIG. 9 is basically an exploded view of the reset solenoid 39 more fully illustrating those elements shown in FIG. 8 and also showing in schematic form the effect upon the complete electrical circuit. As shown in FIGS. 8 and 9, the shaft of the reset solenoid 39 is connected to and drives only the arm 46. The ratchet wheel 45 and plate 39a is connected to and drives a reset cam 51 against a cam wheel 52 and a multisided cam 53 against a cam wheel 54. As mentioned previously, before the decoder can again be interrogated, it is necessary to energize the reset solenoid 39 a second time after the receipt of an error signal. This is accomplished by means of a separate reset channel 55 which is connected through a normally closed reset switch 56 to the open side of a normally closed single pole, double throw switch 57. The operating arm of the switch 57 is electrically connected to the reset solenoid 39. The operating arm of switch 56 is controlled by cam wheel 52 which operates on cam 51. The cam 51 has a single detent to insure that cam wheel 52 will open switch 56 whenever the cam 51 is rotated a preset number of degrees representing a fixed number of errors. Since the cam 51, together with cam 53, are connected together with the ratchet wheel 45, it can be appreciated that whenever the ratchet wheel turns a given number of degrees so as to place the cam wheel 52 in the dwell of the cam 51 that normally closed contacts of switch 56 will open. The cam wheel 54 in addition to controlling the operating arm of the single pole, double throw switch 57 also controls the operating arms of a pair of single pole, double throw switches 58 and 59 which are connected in series with solenoid 11 and 12 respectively. The single pole, double throw switches 57, 58 and 59 are the cycle limit switches and are shown in their normal operating positions with the cam wheel 54 on the relatively low side of the multisided cam 53. Whenever the reset solenoid 39 is energized by an incorrect or error bit the ratchet wheel 45, together with cams 51 and 53 are rotated an amount sufiicient to place the cam Wheel 54 on the high side of the multisided cam 53 for transferring switches 57, 58 and 59. The effect is that with switches 58 and 59 transferred,it becomes impossible for an interrogating signal to energize either rotary solenoid 11 or 12. Referring now to FIG. 6 will show that the transferring of the operating arm of switch 57 from the normally open position establishes a circuit from the reset solenoid 39 through the normally open contacts of switch 57, through the normally closed contacts of switch 56, to the input of the reset channel 55. As mentioned previously in connection with FIG. 7, the receipt of an error bit resulted in the arm 46 being moved to a vertical position thereby locking the tripping lever 48 by latch 50 in a position which allows the code wheel drum It} to return to the first switch position. The error pulse thus energizes the reset solenoid 39 which causes the ratchet wheel 45, the cam 51 and the multisided cam 53 to rotate. Assuming that the error bit is the first error signal received, the cam wheel 52 will not beeffected and switch 56 will remain closed. The position of the multisided cam 52 is such that cam wheel 54 is operated thereby transferring the operating arms of switches 57, 58 and 59. The transferred switches 58 and 59 have the effect of opening the interrogating paths of channels 30 and 31 which prevents either rotary solenoid 11 or 12 to be energized. The transferring of switch 57 however, establishes a path from the reset solenoid 39 to the reset channel 55. The decoder will remain in this position until a second reset pulse is transmitted over reset channel 55, when this is done the reset pulse from channel 55 will pass through the normally closed contacts of switch 56 and through the normally open contacts of switch 57 to energize the reset solenoid 39. The operation of the reset solenoid 39 is described in connection with FIG. 7 is repeated in order to trip latch 50 by the next pin 42 thereby unlocking the tripping lever 48 which has the effect of removing pressure from the keeper 40 and the pawl 15, thereby allowing the keeper 40, the pawl 15 and the tripping lever 48 to assume the position as indicated by the solid lines. The cumulative effect of continually receiving an error signal is that the cam 51 in FIG. 9 is continually advanced until the cam wheel 52 is detented and the operating arm of switch 56 is transferred from the normally closed position to an open opsition. A review of the circuit as shown in FIG. 6 will show that opening switch 56 makes it impossible for a reset pulse from channel 55 to reset the reset solenoid 39. In the preferred embodiment, the angled distance between the cam wheel 52 and the detent on the cam 51 is chosen so that preset number errors can be received before the equipment is finally deenergized. The built-in safety feature is that the equipment will fail safe by becoming completely inoperative rather than pass an incorrect signal. Access to the decoder is then necessary in order to mechanically reset the cam 51.

Continuing now with the exploded view illustrated in FIG. 9 we have described how the ratchet wheel 45, the multisided cam 53 and the reset cam 51 are all mounted coaxially on the shaft of the reset solenoid 39 but driven by the action of the pawl 47 on the ratchet wheel 45. This particular technique of mounting also shown in section in FIG. 8, is for convenience only, since they may obviously have been mounted in any other configuration convenient to the driving mechanism. A keeper 60 is shown bearing against the ratchet wheel 45 in order to hold the ratchet wheel in position whenever the arm 46 is energized by the reset solenoid 39. The keeper 60 is necessary because of a return spring 61 hearing on the shaft of ratchet wheel 45 and tending to return the ratchet wheel to a zero position. The return spring 61 is necessary and used in conjunction with the code resetting feature of the invention in order to return the reset cam 51 to a starting position upon changing of the code and hence provide for a new cumulative number of errors against the new code.

In order to effect the code change, it is first necessary to successfully operate the decoder through a complete cycle of the previous code. It will be appreciated, of course, that once the complete code is entered correctly into the decoder that the output commutator 17 will be completely energized and thereby control the device being protected. As a result, it is necessary during code change to disarm the device by other means (not illustrated or considered part of the presnet invention). Such a device may be a simple relay for opening contacting points in the circuit between the mechanism being protected and the decoder which the operator would control before attempting to change the code. Assuming now that the proper precautions have been initiated which is to remove the device being protected from the output of the decoder by means of a remote relay (not illustrated) it is then necessary to insert the proper code which has the effect of rotating the drum 10 the necessary eighteen switch positions. The rotating drum 10 will wind against the pressure of a negator spring 62 also shown in FIG. 10, which unwinds from a lower drum 63. In the final position of drum 10, the spring 62 will have completely exposed the single detent 63a located in the lower drum 63. Upon the receipt of an additional message bit the drum 10 will be advanced an amount necessary for the cam roller 64 to *be detented into the single detent 63a on the lower drum 63. This is provided by shorting the segments 20 with 21 and segments 23 and 24 in the so-called 19 switch position after the coded switch positions. The cam roller 64 is attached to an arm 65 and a pawl 66 which is arranged to drive a ratchet wheel 67. The ratchet wheel is mechanically connected to a code changing cam 68 having a plurality of arms 69 for engaging the keeper 60 and the pawl 47 which control the reset solenoid ratchet wheel 45. A cam roller 70 is controlled by the detents on the code changing cam 63 which control the transfer of the code changing switches 32 and 35. Whenever the lower drum '63 is moved the additional space passed the eighteenth switch position, the cam roller 70 to fall into one of the detents on the code changing cam 69 to thereby transfer the code changing switches 32 and 35 into the position labeled code change. In addition, the arms 69 contact and cam the keeper 60 and pawl 47 away from the ratchet Wheel 45 thereby allowing the return spring 61 to rotate the ratchet wheel 45 back to the predetermined original starting position. Since the reset cam 51 is physically connected to the ratchet wheel 45, the single detent on the reset cam is then repositioned an amount away from the cam roller 52 to allow 'for additional errors. The transferred code change switches 32 and 35 located in the input channels 30 and 31 respectively now channel any input signal directly to the associated solenoid. Cam wheel 70, in addition, transfers an additional code change switch 71 located in the reset channel 55 from a normally open position to a closed position. In order to reset the code wheel drum 10 back to the first switch position, it is necessary to energize the reset solenoid 39 with a pulse entering into channel 55. The reset channel 55 now comprises a path consisting of the normally closed contact of switch 56, through the normally open contact of switch 71 to the reset solenoid 39. The energizing of the reset solenoid 39 will operate the tripping lever 48 as previously described which trips the keeper 40 and the pawl 15 which allows the code wheel drum 10 to return to the original first switch position. Since the reset solenoid 39 has been energized, the associated multisided cam 53 is rotated together with cycle limiting cam 51. In order to unlatch the tripping lever 58, an additional, or second pulse is transmitted along the reset channel 55 through the normally closed contact 56 and through either the normally open contact of switch 57 or the normally open contact of switch 71 to energize the reset solenoid 39 for tripping the latch 50, and rotating the multisided cam 53 for transferring switches 57, 58 and 59 to their normally closed positions. The code wheel commutator 10 is now at the first switch starting position and is ready to accept a new code. In this position, the cam wheel 70 is still on the dwell of cam 68 maintaining the normally open contacts of switch 71, switch 32 and switch 35 in a transferred closed position.

The following description for entering the new code will be made more apparent by referring now to FIGS. 3, 6 and 11. FIG. 11a illustrates a coded sequence of pulses for interrogating channels 30 and 31 as determined by the positions of the contactor actuating rods 25 in FIG. 5.

FIG. 11b illustrates the necessary pulses that are trans mitted to both channels 30 and 31 for repositioning the actuating rods 25 to effect the code as illustrated in FIG. 11a. For example, with the code wheel drum returned to the first switch position, the first step necessary to insert the new code is to pulse both channels 36) and 31 simultaneously. As shown in FIG. 6, both code changing switches 32 and 35 are transferred thereby presenting a direct path from input channel 30 to solenoid 11 which is energized and a direct path from channel 31 to solenoid 12 which is energized. With the solenoids 11 and 12 energized, an independently supported cam roller 72 cooperating with the pawl 15- and a similar cam roller 73 cooperating with pawl 16 are both cammed against the drum 10 by means of camming surface 74 and 75 located on the driving means of rotary solenoids 11 and 12 that move pawls 15 and 16, respectively.

The roller cams 72 and 73 contact the drum 10 between the protruding rods 25. As mentioned previously, the code wheel drum 10 does not move until power is removed. Since power is applied to both channels, power is removed from channel 31 (see FIG. 11b) thereby allowing pawl 16 to move under spring tension (not illustrated) for rotating the code wheel drum 10. This action moves the code wheel drum 1% to the next switch position, however, during this time power was not removed from channel 30 which remained energized and caused cam wheel 72 to bear against rotating drum 10 The cam wheel 72 exerted a pressure on the protruding contactor actuating rod thereby causing the contactor actuating rod to assume a position as indicated by the solid lines in FIG. 5 for setting up a code requiring a signal from channel 31 as shown in FIG. lla. The code wheel drum 10 is now in the second switch position preparatory to setting up the actuating rod 25 for that position. In order to establish the proper position of the contacting actuator rod for the second switch position, it is again necessary to pulse both channels and 31 and repeat the procedure. Removing power from channel 30 allows pawl 15 to rotate the drum 10 thereby causing the roller cam 73 to position rod 25. A review of the contacting elements associated with the contactor actuating rods 25 will show that the proper interrogating pulse for the second switch position will be a pulse on channel 30. The same procedure is followed for all switch positions in that first, both channels are energized and then power is removed from that channel which corresponds to the proper or desired code. After the last of the contactor actuating rods 25 has been positioned, power is removed from the remaining channels thereby advancing the drum which exposes the single detent on the lower drum 63 (illustrated in FIG. 9) which allows the cam wheel 64 to operate the pawl 66 for rotating the ratchet wheel '67 and the code change cam 68. Moving the code change cam 63 causes the cam wheel 74} to rise off the dwell thereby transferring the code change switches 32, 35 and 71 (FIGS. 6 and 9) back to the normal position.

The code wheel drum 10 is reset by purposefully energizing either channel 30 or 31 to thereby energize the reset solenoid 39. Once the reset solenoid 39 is energized, the code wheel drum 10 will return to the first switch position. In order to prepare the decoder for proper interrogation of the new code, it is now necessary to again energize the reset solenoid 39 by means of the reset channel 55. The circuit will include reset channel 55, switch 56 and the normally open contacts of switch 57 to the reset solenoid 39. This completes the code changing procedure and the decoder is now ready to accept interrogating signals representative of the new code just inserted.

There is still another feature of the invention illustrated in FIG. 10 which shows an associated device for removing coded information in the event the decoder is physically moved from a preferred position. This feature insures that whether the decoder is being repaired and removed in an approved manner or remove-d or tampered within an unapproved manner that any code previously inserted will be automatically cancelled, thereby removing the possibility that prying eyes can determine the last code inserted. Assume, for example, that the decoder is to be located in a device having a preferred vertical position, and that a deviation of the device from a vertical position is to be sensed and detected as an unauthorized deviation which will require the immediate removal of the coded information from the code wheel drum 10. Referring now to FIG. 10 there is shown a sump 74 arranged to contain, for example, a head of mercury which feeds through a suitable tube 75 into a bellows arrangement 76. With the sump 74 in a vertical position, the head of mercury will be suficient to expand the bellows 76 thereby maintaining pressure on an actuating arm 77. The actuating arm 77 maintains a pressure against levers 78, 79 and 80 which are attached together and shown in solid lines. Should the sump 74 be tilted from a vertical positron, the mercury will flow into the sump 74 thereby removing the pressure from the bellows '76 and release the pressure from the actuating rod 77 thereby allowing levers 78, 79 and 80 to assume a position indicated by the dotted lines 78a, 79a and 89a. In the normal position, pawl 15 and keeper 40 will contact ratchet wheel 13 on the code wheel drum 10 as indicated by the solid lines 15 and 40. The outermost end of lever 86 contains a roller cam 82 arranged to contact one side of the code wheel drum 10. The triggered position is shown by the cam 82a which earns the protruding ends of the contactor actuating rods 25. One end of arm 78 contains a hook member 83 which normally engages a stop 84 attached to the code wheel drum 10. Under proper conditions, the pawl 15 operates against the teeth on the ratchet 13 for advancing the code wheel drum 19 in response to. the properly received interrogating signals. This action will cause negator spring 62 to unwind from lower drum 63 and wind on the upper drum 85. In those cases where an incorrect interrogating signal is received and the code wheel drum It) is returned to the first switch position, the mechanical stop is by means of pin 84 contacting the hook member 83. Considering now the situation in which the device is tilted from vertical, we have shown that arms 78, 79 and 80 will assume the position as indicated by dotted lines 78a, 79a and 80a. In this position, the keeper 4d and pawl 15 will be cammed away from the ratchet wheel 15 as indicated by the dotted positions 4% and 15a, thereby allowing the code Wheel commutator 10 to rotate under the action of the negator spring 62 which rewinds the spring from upper drum 85 to the lower drum 63. The code wheel commutator 10 in rotating will cause the protruding ends of the contactor actuating rods 25 to contact the cam wheel now in position 82a. The elfect is that as the code wheel drum 11) is rotated under the action of the negator spring 62 and that all the contactor actuating rods 25 will be pushed to one side thereby removing any evidence of the previous code that was placed in the code wheel commutator 10. In order to insure that all of the contactor actuating rods 25 are acted upon, the hook end 83 is also displaced to the position indicated by the dotted line 83a, thereby allowing the code wheel commutator 10 to rotate many revolutions and ultimately be stopped by means of a stop mechanism 86 contacting a detent 87 associated with the upper drum 85. A physical inspection of the code wheel drum 10 will reveal no information concerning the code previously inserted.

This completes the description of the embodiment of the invention illustrated herein. However, many modifications and advantages thereof will be apparent to persons skilled in the art without departing from the spirit and scope of this invention. Accordingly, it is desired that this invention not be limited to the particular details of the embodiment disclosed herein, except as defined by the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In combination,

a plurality of individually controlled switches in an ordered relationship,

each of said switches being preset for establishing a plurality of paths of which only one is a preferred path,

interrogating means for individual interrogating said preset paths, and

switch selecting means responsive to said interrogating means selecting said preferred path for sequentially selecting the next of said switches in said ordered relationship to be interrogated.

2. In combination,

a plurality of individually controlled switches in an ordered relationship,

each of said switches being preset for establishing at least two paths of which only one is a preferred path,

interrogating means for individually interrogating said preset paths,

switch selecting means responsive to said interrogating means selecting said preferred path for sequentially selecting the next of said switches in said ordered relationship to be interrogated, and

disabling means responsive to said interrogating means selecting a path other than said preferred path for interrupting said interrogating means.

3. In combination,

a plurality of individually controlled switches in an ordered relationship,

each of said switches being preset for establishing a plurality of paths of which only one is a preferred path,

interrogating means for individually interrogating said preset paths,

switch selecting means responsive to said interrogating means selecting said preferred path for sequentially selecting the next of said switches in said ordered relationship to be interrogated,

and output means controlled by the selection of said preferred path in the last of said switches in said ordered relationship.

4. In combination,

a plurality of individually controlled switches in an ordered relationship,

each of said switches being preset for establishing a preferred path,

means for interrogating a first switch in said ordered relationship by channeling an interrogation signal through said preferred path associated with said first switch, and

sequential selecting means response to said interrogation signal passing through said preferred path for selecting the next of said switches in said ordered relationship to be interrogated.

5. In combination,

a plurality of individually controlled switches in an ordered relationship,

each of said switches being preset for establishing at least two paths of which only one is a preferred path,

interrogating means for interrogating a first switch in said ordered relationship by channeling in interrogation signal through said preferred path associated with said first switch,

stepping means responsive to said interrogation signal passing through said preferred path for sequentially selecting the next of said switches in said ordered relationship to be interrogated,

and disabling means responsive to said interrogataing means selecting a path other than said preferred path for interrupting said interrogating means.

6. In combination,

a plurality of individually controlled switches in an ordered relationship,

each of said switches being preset for establishing at least two paths of which only one is a preferred path,

interrogating means for interrogating a first switch in said ordered relationship by channeling an interrogation signal through said preferred path associated with said first switch,

selecting means responsive to said interrogation signal passing through said preferred path for sequentially selecting the next of said switches in said ordered relationship to be interrogated,

disabling means responsive to said interrogating means selecting a path other than said preferred path for interrupting said interrogating means, and

output means controlled by the selection of said preferred path in the last of said switches in said ordered relationship.

7. In combination, 7

a plurality of individually controlled switches in an ordered relationship,

each of said switches being preset for establishing at least two paths of which one is a preferred path,

a plurality of interrogating means one for each path connected in circuit for passing an interrogating signal through said preferred path,

switch selecting means responsive to said interrogating signal passing through said preferred path for selecting the next of said switches in said ordered relationship to be interrogated,

means for interrupting said interrogating means circuit upon the selection of a path other than said preferred path by said interrogating means,

and output means controlled by the selecting of said preferred paths in all of said switches.

8. In combination,

a plurality of individually controlled switches in an ordered relationship,

each of said switches being preset for establishing at least two paths of which one is a preferred path,

a plurality of interrogating means one for each path connected in circuit for passing an interrogating signal through said preferred path,

switch selecting means responsive to said interrogating signal passing through said preferred path for selecting the next of said switches in said ordered relationship to be interrogated,

means for interrupting said interrogating means circuit upon the selection of a path other than said preferred path by said interrogating means,

and output means controlled by the selection of said preferred path in the last of said switches in said ordered relationship.

9. In combination,

a plurality of individually controlled switches in an ordered relationship,

each of said switches being preset for establishing at least a first path and a second path,

means for selectively interrogating said paths by passing an interrogating signal through one of said paths,

switch selecting means responsive to said interrogating signal passing through said first path for selecting the next of said switches in said ordered relationship to be interrogated,

means responsive to said interrogating signal passing through said second path for interrupting said interrogating means,

and output means controlled by the selection of said first path in all of said switches.

10. In combination,

a rotatable drum including a plurality of individually controlled switches,

each of said switches defining at least two paths of which one is a selected path, means for interrogating only a single path, and means for rotating said drum to the next switch position in response to the interrogation of said selected path.

11. In combination, a rotatable drum including a plurality of individually controlled switches in an ordered relationship,

each of said switches capable of establishing at least two paths of which one is a preselected path,

means for selectively interrogating only one path for each switch by passing an interrogating signal through said path,

switch selecting means responsive to said interrogating signal passing through said preselected path for rotating said drum to the next switch position in said ordered relationship,

and output means controlled by the selection of said preselected paths in all of said switch positions.

12. A combination according to claim 11 which includes code changing means for sequentially presetting each of said switches,

said code changing means being operable only after all of said switches have been properly interrogated.

13. In combination, a rotatable drum comprising a plurality of individually controlled switches in an ordered relationship,

each of said switches capable of establishing at least two paths,

means for presetting each of said switches to establish one of said paths henceforth called a preferred path,

interrogating means for sequentially interrogating a selected path of each switch position by passing an interrogating signal through said selected path,

switch selecting means responsive to said interrogating signal passing through said preferred path for rotatin g said drum to the next of said switches in said ordered relationship,

means responsive to said interrogating signal passing through the other of said paths for interrupting said interrogating means,

and output means controlled by the selection of said preferred paths in all of said switches.

14. In combination, a rotatable drum comprising a plurality of individually controlled switches in an ordered relationship,

each of said switches capable of establishing at least two paths, means for presetting each of said switches to establish a preferred path,

interrogating means for sequentially interrogating a selected path of each switch position by passing an interrogating signal through said selected path,

switch selecting means responsive to said interrogating signal passing through said preferred path for rotating said drum to the next of said switches in said .ordered relationship,

means responsive to said interrogating signal passing through the other of said paths for interrupting said interrogating means,

reset means for resetting said interrogating means by returning said drum to the first switch position in said ordered relationship,

said reset means having a limited number of resets that is less than the number of switch positions,

and output means controlled by theselection of said preferred paths in all of said switches.

15. In combination, a rotatable drum having a preferred orientation and comprising a plurality of individully controlled switches in an ordered relatonship,

each of said switches capable of establishing at least two paths, means for presetting each of said switches to establish a preferred path,

interrogating means for sequentially interrogating a selected path of each switch position by passing an interrogating signal through said selected path,

switch selecting means responsive to said interrogating signal passing through said preferred path for rotating said drum to the next of said switches in said ordered relationship,

mean responsive to said interrogating signal passing through the other of said paths for interrupting said interrogating means,

means for arbitrarily changing the selected position of said switches in response to said drum being moved from said preferred orientation,

and output means controlled by the selection of said preferred paths in all of said switches.

16. In combination, a rotatable drum comprising a plurality of individually controlled switches in an ordered relationship located on the periphery of said drum,

each of said switches capable of establishing a first path and a second path,

means for presetting each of said switches to establish one of said paths henceforth called a preferred path,

a pair of input channels each connected to one of said paths,

means for interrogating one of said channels by generating and transmitting an interrogating signal through one of said paths,

switch selecting means one for each channel located on each side of said drum responsive to said interrogating signal passing through said preferred path for rotating said drum to the next of said switches in said ordered relationship,

means responsive to said interrogating signal from said other channel passing through the other .of said paths for interrupting said interrogating means,

and output means controlled by the selection of said preferred paths in all of said switches.

17. In combination, a rotatable drum comprising a plurality of individually controlled switches in an ordered relationship located on the periphery of said drum,

each of said switches capable of establishing a first path and a second path,

means for presetting each of said switches to establish one of said paths henceforth called a preferred path,

each of said paths being connected to a separate input channel,

means for interrogating one of said channels by generating and transmitting an interrogating signal through said selected path,

a pair of switch selecting means one for each channel located on each side of said drum, one of said switch selecting means responsive to said interrogating signal passing through said preferred path for rotating said drum to the next of said switches in said ordered relationship,

means responsive to said interrogating signal passing through the other of said channels for interrupting said interrogating means,

and output means controlled by the selection of said preferred paths in all of said switches.

18. In combination, a rotatable drum comprising a plurality of individually controlled switches in an ordered relationship located on the periphery of said drum,

each of said switches capable of establishing a first path and a second path,

means for presetting each of said switches to establish one of said paths henceforth called a preferred path,

each of said paths being connected to a separate input channel,

means for interrogating one of said channels by generating and transmitting an interrogating signal through said selected path,

a pair of switch selecting means one for each channel located on each side of said drum, one of said switch selecting means responsive to said interrogating sig- 15 nal passing through said preferred path for rotating said drum to the next of said switches in said ordered relationship,

means responsive to said interrogating signal passing through the other of said channel for interrupting said interrogating means,

and output means controlled by the selection of said preferred paths in all of said switches.

19. -In combination, a rotatable drum comprising a plurality of individually controlled switches in an ordered relationship located on the periphery of said drum,

each of said switches capable of establishing a first path and a second path,

means for presetting each of said switches to establish one of said paths henceforth called a preferred path,

each of said paths being connected to a separate input channel,

means for interrogating one of said channels by generating transmitting an interrogating signal through said selected path,

a pair of switch selecting means one for each channel located on each side of said drum, one of said switch selecting means responsive to said interrogating signal passing through said preferred path for rotating said drum to the next of said switches in said ordered relationship,

means responsive to said interrogating signal passing through the other of said channel for interrupting said interrogating means,

reset means for resetting said interrogating means by returning said drum to the first switch position in said ordered relationship,

said reset means having a limited number of resets that is less than the number of switch positions,

and output means controlled by the selection of said preferred paths in all of said switches.

20. In combination, a rotatable drum comprising a plurality of individually controlled switches in ordered relationship located on the periphery said drum,

each of said switches capable of establishing a first path and a second path,

means for presetting each of said switches to establish one of said paths henceforth called a preferred path,

each of said paths being connected to a separate input channel,

means for interrogating one of said channels by generating and transmitting an interrogating signal through said selected path,

a pair of switch selecting means one for each channel located on each side of said drum, one of said switch selecting means responsive to said interrogating signal passing through said preferred path for rotating said drum to the next of said switches in said ordered relationship,

means responsive to said interrogating signal passing through the other of said channel for interrupting said interrogating means,

means for arbitrarily changing the selected position of said switches in response to said drum being moved from said preferred orientation,

and output means controlled by the selection of said preferred paths in all of said switches.

an of References Cited by the Examiner UNITED STATES PATENTS 7/1951 Curry 340-l64 6/1957 Barnhart 340l64 X 

1. IN COMBINATION, A PLURALITY OF INDIVIDUALLY CONTROLLED SWITCHES IN AN ORDERED RELATIONSHIP, EACH OF SAID SWITCHES BEING PRESET FOR ESTABLISHING A PLURALITY OF PATHS OF WHICH ONLY ONE IS A PREFERRED PATH, INTERROGATING MEANS FOR INDIVIDUAL INTERROGATING SAID PRESET PATHS, AND SWITCH SELECTING MEANS RESPONSIVE TO SAID INTERROGATING MEANS SELECTING SAID PREFERRED PATH FOR SEQUENTIALLY SELECTING THE NEXT OF SAID SWITCHES IN SAID ORDERED RELATIONSHIP TO BE INTERROGATED. 